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What are the properties of mirrors?
M.S 158, Flushing NY US
Here's a really basic general property: a light ray that strikes a
mirror at an angle, will reflect off at the same angle. (angle of
incidence equals angle of reflection.) That means that patterns in the
light are preserved, unlike when light bounces off ordinary surfaces in
all different directions.
Some of the consequences of the basic law follow. A mirror that is
concave (the mirror side is on the inside of the curve) will focus
light rays and form a real image of the object. For light that comes in
from a long ways out, all the beams get focused to a single point
called the focus point - very similar to how a magnifying glass works.
for a convex mirror (the mirror side is on the outside of the
curve) the light rays form what is called a virtual image. Virtual
images look like that are behind the mirror but are not formed by any
actual light rays.
(republished on 07/29/06)
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